Brake device for rolling-mills.



A. A. K. NOWAK.

BRAKE DEVICE FOR ROLLING MILLS.

APPLICATION IILED FEB.28, 1911.

Patented Oct. 15; 1912.

WITNESS S w ATTORNEYS UNITED STATES FATE BRAKE DEVICE FOR BOLLING-MILLS.

' Specification 0! Letters Patent.

Application filed February 28, 1911. Serial No. 811,384.

To all whom it may concern:

Be it known that I, ADOLF ALEXANDER KARL NOWAK, a subject of the Emperor of Austria-Hungary, and residing at Bous-onthe-Saar, Germany, have invented a certain new and Improved Brake Device for Belling-Mills, of which the following is a specification.

My invention relates to rolling mills of the reciprocating step-by-step "advance type commonly employed in rolling seamless tubes and the special object of my invention is to supply-a suitable brake device for mills of this type. v

In mills of the reciprocating step-by-step advance type the blank is ordinaril advanced to the stationary forming rolis under pressure from a return spring or the like, and astop is arranged behind the rolls against which the conically shaped portion of the blank lying between the reduced tube and the yet unreduced blank impinges thus positioning the blank for the next attack of the rolls. Heavy thrusts are thus set up which are very injurious toboth the mill and to the blank. To relieve these thrusts bufi'er springs or air cushions have been suggested but have proved for the most part unsatisfactory and impracticable in mills of the larger sort. Such buffer brakes do not old viate the necessity for the impingement of the blank against the stop, since the latter is relied upon to secure the proper positioning of the blank for the next attack of the rolls. It is clear that resilient brakes of this character cannot be permitted to completely take up the thrust of the blank since the latter must be permitted to fully reach its position between the forming rolls and inasmuch as the effort of the buffer springs as they are compressed, is to return the blank before reaching the rolls, the compression of the springs must be so regulated that the blank is permitted to reach its extreme position, and thiscannot be determined in practice with suliicicnt nicety to obviate the I necessity for'the impingement of the'blank against the stop, with the conse uent objectionable thrusts which result. 'imilar difficulties *attend the use of air cushions. Here it is possible to besure, to somewhat lessen the undesirable rebound of the blank, by permitting a portion of the compressed air to escape just before the blank reaches its extreme position. But in use these air cushions have disclosed many impracticable features. It is especially difficult to secure and, maintain an efficient packing for the piston which will not leak under the heavy pressure to which it is subjected. Mills provided with air cushions also are found to work very unevenly, a feature especially un- Patented Oct. 15,1912.

desirable in large mills, and in the latter it is consequently necessary to employ both types of buffers as a matter of safety. And it is in these heavy millsthat it is particularly desirable to find some means to take up the thrust, since not only does the stop anvil have to be made very heavy but the vibrations caused by the impingement of the blank against the same very seriously disturb the smooth working of the rolls.

The present invention provides meansfor accomplishing this much desired result, through a fluid brake arranged on the mandrel stem. Inasmuch as fluids such as water, glycerin, etc, are practically incompressible, a brake of this character may be provided, as experiments have proven, which not only takes up completely the thrust of the advancing blank but also permits the latter to reach its extreme position between the rolls and without any tendency to rebound.

In view of the fact that the rapid work? ing of t e piston in the brake cylinder soon heats the brake fluid and tends to cause steam to generate, it is wise to build theforward portion of the brake cylinder heavy, 1

ger is retracted fresh fluid enters the cylind er and is'agai'n forced out as the plunger enters, thus causing a circulation of the fluid which lessens its tendency to heat up in the brake cylinder.

The present invention also contemplates I the provision of suitable means for cooling the fluid in the container, for example by a cooling coil., Furthermore, ifthe container be arranged so as to surround the brake cyiinder, the latter will be. further cooled by the fluid jacket. In any case it is possible to employ a fluid of high boiling point inorder toavoid the dangerous generation of steam.

However, inasmuch as the fluidity of certain substances varies with its temperature, for example, glycerin, temperature regulation is a matter of considerable importance for the proper working of .the brake.

Experiments have shown that even in heavy mills (for rolling tubes of 300 mm. diameter and above) the thrust is entirely eliminated by using a brake of the type described. Nevertheless should the blank impinge against the stop, the latter serves as a safety device and particularly as a signal to the mill attendant to regulate the feed of the blank to the rolls. The brake is normally so arranged that during a proper feed of the blank to the rolls it will not impinge against the stop. Should this happen however, it is a signal to the attendant that the feed nizust be retarded. Consequently in new mills it will be necessary to form the stop only as a weak ring or the like, fast with the roll frame. Further experiments have shown that, usin such a brake, even the largest mills -wor practically noiselessly if the blank is advanced to the rolls by a compressedaircylinder.

In the accompanying drawing, a rolling mill is diagrammatically shown in longitudinal section and equipped with my fluid brake in oneform.

Referring to the drawing, it will be noted that at the rear end of the mandrel rod f is secured. the plunger a of a fluid brake. This plunger is reduced at a and the smaller end a enters the constricted end of the brake cylinder g, which cylinder communicates through ports a, 2' with the surrounding chamber of the fluid container is. The latter is so arranged that the brake cylinder is enveloped throughout its length by the brake fluid/ A cooling coil Z may be arranged in the container as shown.

Both the brake cylinder 9 and the compressed air cylinder m, for advancing the blank, are mounted on the usual slide 3, which is step-by-step advanced toward the rolls by any well known means during the intervals between the attacks of the latter upon the blank, as is the common practice.

The blank w is driven back by the attack of the rolls, in the direction of the arrow Z to the right, together with the mandrel d and mandrel rod f. The brake plunger a, fast with the rod f. partakes of this motion and sucks the brake fluid into the cylinder through the ports 2', 2' from the container is, while at the same time the air in cylinder at is compressed in a container of any suitable character, for example the cylinder at. On the return of the blank in the direction of the arrow 2, under the influence of the compressed air in cylinder m, the fluid in the brake cylinder is driven out at first through ports 2' and i but as soon as the-coned portion a of the plunger haspessed the port i only the port '5 remains for the escape of the brake fluid during the advance of the plunger. After the small end a of the plunger a, toward the end of the advance of the blank, enters the constricted portion of the cylinder g, the fluid ahead of the plunger can escape only through the narrow annular space between the plunger a and cylinder g, so that the brake is now under its greatest stress and the advance of the blank is brought to an end. The point at which this is accomplished depends upon the form of the plunger a and of the cylinder g,' but it remains practically constant if the pressure from the cylinder he remains the same. It is necessary therefore that care be taken to insure the, even and uniform working of'the pressure cylinder. If coil springs were to be employed, the tension of the spring must be re ulated, while with acompressed air cylin er it is necessary to insure the return of the work'to the same point only, after each attack. In the present arrangement the attendant has only to regulate the feed of the slide 8. This is much safer than the other methods of regulation, especially in heavy mills where the thrusts which occur are very heavy. Furthermore, when the present fluid brake is used and light thrusts occur through the impingement of the blank against the safety stop an, this but serves as an indication to the attendant that the feed should be retarded. As a rule, the feed can be so regulated that no thrust occurs.

The invention is of particular utility inasmuch as the brake may be applied to mills provided with any suitable feed device. The hitherto necessary bufl'er springs may be dispensed with, and also the uneyenly working air cushions.

Obviously more than a single brake plunger may be usedand the arrangement may be variously modified within the scope of the appended claims;

I claim as my invention-:

1. A brake device for rolling mills of the type described, eomprising a plunger moving with the mandrel rod, and a fluid brake cylinder arranged to cooperate with said plunger,'.and a fluid container secured to said cylinder and communicating therewith to admit to and receive from said cylinder at braking fluid during the operation of the plunger, together with means for cooling the fluid in said container.

2. A brake devicefor rolling mills of the type described, comprising a plunger moving with the mandrel rod, and a fluid brake cylinder arranged to cooperate .With said plunger, and a fluid container surrounding said cylinder and communicatingtherewith to. admit to and receive from said cylinder a braking fluid during the operation of the plunger.

3. A rolling mill having a mandrel rod,

a compressed air 'device for advancing the same, and a fluid brake employing a noncompressible 'fluid, coiiperating with the mandrel rod to halt its advance at a predetermined point, substantially as described.

4. A rolling mill having a mandrel rod, a brake plunger moving therewith, a compressed air device for advancing said mandrel rod and a fluid brake cylinder employinga non-compressible fluid, arranged to coiiperate with the brake plunger to halt the advance of the mandrel rod at a predetermined point, substantially as described.

5. A brake device for rolling mills of the type described, comprising a fluid brake ele-' ment moving with the mandrel slide and a coiiperating element moving with the mandrel, substantially as described.

6. A brake device for rolling mills of the type described, comprising a fluld brake cylinder carried by the mandrel slide and a 00- operating brake plunger operatively connected to the mandrel, substantially as described. I

In testimony whereof I have signed my name to this specification, in the presence of two subscribing Witnesses.

ADOLF ALEXANDER KARL NOWAK.

Witnesses M. BRUXMEIER, T. FISCHER. 

